Etching Solutions

ABSTRACT

The present invention provides an etching solution for silver or silver alloy comprising one at least ammonium compound represented by the formula (1), (2) or (3) below and an oxidant.

TECHNICAL FIELD

The present invention relates to an etching solution for silver orsilver alloy.

BACKGROUND ART

According to Ullmann's Encyclopedia of Ind. Chem., Vol. A24, 107 (1993),silver is a precious metal resistant to oxidation, having goodelectrical and thermal conductivity, and having catalytic andantimicrobial activity. Therefore, silver and silver compounds arewidely used in industries, including alloy, plating, medicine,photography, electrics/electronics, fiber, detergent and householdappliances. In addition, silver compounds can be used as catalyst in thesynthesis of organic materials and polymers. Particularly, as use oflead in electrical and electronic circuits is regulated, silver isdrawing attention as the material for metallic pattern and electrode insuch emerging applications as low-resistance metal wirings, printedcircuit boards (PCB), flexible printed circuits (FPC), antennas forradio frequency identification (RFID) tags, EMI shielding plasma displaypanels (PDP), thin film transistor liquid crystal displays (TFT-LCD),organic light emitting diodes (OLED), flexible displays and organic thinfilm transistors (OTFT).

Recently, researches on using silver instead of aluminum as the materialfor reflection film in reflection type or semi-transmission type LCDs,are actively in progress, as disclosed in Japanese Patent Laid-Open No.2002-129259 (May 9, 2002), Japanese Patent Laid-Open No. 2004-176115(Jun. 24, 2004) and Japanese Patent Laid-Open No. 2004-231982 (Aug. 19,2004), because silver has better reflection and conduction propertiesthan aluminum. Thus, there is a need for development of etchingsolutions for silver. Until now, etching of metal wiring or film isperformed mostly using plasma or etching solutions. When conventionaletching solutions for aluminum, which comprise phosphoric acid, nitricacid, acetic acid and water in general, are used for silver, thefollowing problems occur: 1) other than silver, metal or metal oxide maybe etched, too; 2) a superior pattern cannot be attained; 3) offensiveodor makes working conditions unpleasant.

In general, etching of metal is accomplished by repeating the process ofoxidation of metal surface by an oxidant to produce metal oxide, whichis dissolved by an oxide dissolver. Currently, dissolution of silver isperformed, in general, using a highly oxidative acid such as nitric acidor a mixture of an iron-based oxidant such as ferric sulfate and aninorganic acid such as phosphoric acid, sulfuric acid and acetic acid,as disclosed in Japanese Patent Laid-Open No. 2004-238656 (Aug. 26,2004). Korean Patent Publication No. 2004-48374 (Jun. 9, 2004) presentsan etching solution comprising a polyvalent carboxylic acid such asoxalic acid and succinic acid and an inorganic acid such as phosphoricacid and nitric acid. And, Korean Patent Publication No. 2004-440343(Jul. 5, 2004) and Korean Patent Publication No. 2004-440344 (Jul. 5,2004) present an etching solution comprising hydrogen peroxide, anorganic acid and a pH adjuster or one comprising a trivalent ironcompound as oxidant, nitric acid, acetic acid and an amine compound.But, use of strong inorganic acid results in corrosion, staining orreduced stability. U.S. Pat. No. 3,860,423 (Jan. 14, 1975) presents anetching solution for silver comprising ammonia and hydrogen peroxide.But, it shows slow etching rate in some instances. Therefore,development of a new etching solution is needed for etching of thinsilver film or for superior pattern formation.

The present inventors ardently worked to solve these problems and foundthat when an oxidant is added to at least one ammonium compoundrepresented by the formula (1), (2) or (3) below, the resultant solutioncan dissolve silver or silver alloy. Thus, the present inventionprovides an etching solution for silver or silver alloy, which is notnon-corrosive and stable, while offering superior etching performanceand enabling reuse.

DISCLOSURE [Technical Problem]

An object of the present invention is to provide an etching solution forsilver or silver alloy comprising at least one ammonium compoundrepresented by the formula (1), (2) or (3) below and an oxidant.

Another object of the present invention is to provide an etchingsolution for silver or silver alloy being non-corrosive, offeringsuperior stability and etching performance and enabling reuse.

Also another object of the present invention is to provide a method forpreparing said etching solution for silver or silver alloy.

[Technical Solution]

To attain the objects, the present provides an etching solution forsilver or silver alloy comprising at least one ammonium compoundrepresented by the formula (1), (2) or (3) below and an oxidant:

each of R₁, R₂, R₃, R₄, R₅ and R₆ is, independently, selected fromhydrogen; substituted or unsubstituted C₁-C₃₀ aliphatic alkyl, alicyclicalkyl, aryl or aralkyl; a polymer compound; a heterocyclic compound; andderivatives thereof and R₁ and R₂ or R₄ and R₅ may be connected to forma ring. However, the present invention is not particularly limited tothis description.

Specific examples of R₁, R₂, R₃, R₄, R₅ and R₆ in the formula (1), (2)or (3) are hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl,amyl, hexyl, ethylhexyl, heptyl, octyl, isooctyl, nonyl, decyl, dodecyl,hexadecyl, octadecyl, docodecyl, cyclopropyl, cyclopentyl, cyclohexyl,allyl, hydroxy, methoxy, hydroxyethyl, methoxyethyl, 2-hydroxy propyl,methoxypropyl, cyanoethyl, ethoxy, butoxy, hexyloxy, methoxyethoxyethyl,methoxyethoxyethoxyethyl, hexamethyleneimine, morpholine, piperidine,piperazine, ethylenediamine, propylenediamine, hexamethylenediamine,triethylenediamine, pyrrole, imidazole, pyridine, carboxymethyl,trimethoxysilylpropyl, triethoxysilylpropyl, phenyl, methoxyphenyl,cyanophenyl, phenoxy, tolyl, benzyl and derivatives thereof, polymercompounds such as polyallylamine and polyethyleneimine and derivativesthereof. But, the present invention is not particularly limited by theseexamples.

Specific examples of the ammonium carbamate compound represented by theformula (1) are ammonium carbamate, ethylammonium ethylcarbamate,isopropylammonium isopropylcarbamate, n-butylammonium n-butylcarbamate,isobutylammonium isobutylcarbamate, t-butylammonium t-butylcarbamate,2-ethylhexylammonium 2-ethylhexylcarbamate, octadecylammoniumoctadecylcarbamate, 2-methoxyethylammonium 2-methoxyethylcarbamate,2-cyanoethylammonium 2-cyanoethylcarbamate, dibutylammoniumdibutylcarbamate, dioctadecylammonium dioctadecylcarbamate,methyldecylammonium methyldecylcarbamate, hexamethyleneiminiumhexamethyleneiminecarbamate, morpholinium morpholinecarbamate,pyridinium ethylhexylcarbamate, triethylenediaminium isopropylcarbamate,benzylammonium benzylcarbamate, triethoxysilylpropylammoniumtriethoxysilylpropylcarbamate, etc. Specific examples of the ammoniumcarbonate compound represented by the formula (2) are ammoniumcarbonate, ethylammonium ethylcarbonate, isopropylammoniumisopropylcarbonate, n-butylammonium n-butylcarbonate, isobutylammoniumisobutylcarbonate, t-butylammonium t-butylcarbonate,2-ethylhexylammonium 2-ethylhexylcarbonate, 2-methoxyethylammonium2-methoxyethylcarbonate, 2-cyanoethylammonium 2-cyanoethylcarbonate,octadecylammonium octadecylcarbonate, dibutylammonium dibutylcarbonate,dioctadecylammonium dioctadecylcarbonate, methyldecylammoniummethyldecylcarbonate, hexamethyleneiminium hexamethyleneiminecarbonate,morpholinium morpholinecarbonate, benzylammonium benzylcarbonate,triethoxysilylpropylammonium triethoxysilylpropylcarbonate,triethylenediaminium isopropylcarbonate, etc. Specific examples of theammonium bicarbonate compound represented by the formula (3) areammonium bicarbonate, isopropylammonium bicarbonate, t-butylammoniumbicarbonate, 2-ethylhexylammonium bicarbonate, 2-methoxyethylammoniumbicarbonate, 2-cyanoethylammonium bicarbonate, dioctadecylammoniumbicarbonate, pyridinium bicarbonate, triethylenediaminium bicarbonate,etc.

The particular ammonium compound represented by the formula (1), (2) or(3) or the preparation method thereof needs not be restricted inparticular. For example, the ammonium carbamate compound can be obtainedfrom the reaction primary amine, secondary amine or tertiary amine withcarbon dioxide and the ammonium carbonate compound and the ammoniumbicarbonate compound can be obtained by addition of water, as disclosedin U.S. Pat. No. 4,542,214 (Sep. 17, 1985), J. Am. Chem. Soc., 123,p10393 (2001) and Langmuir, 18, p71247 (2002). The reaction may becarried out under normal pressure or applied pressure with or without asolvent. In case a solvent is used, water, alcohols such as methanol,ethanol, isopropanol, butanol and ethanolamine, glycols such as ethyleneglycol and glycerine, acetates such as ethyl acetate, butyl acetate andcarbitol acetate, ethers such as diethyl ether, tetrahydrofuran anddioxane, ketones such as methyl ethyl ketone and acetone, hydrocarbonsolvents such as hexane and heptane, aromatic solvents such as benzeneand toluene, halogen-substituted solvents such as chloroform, methylenechloride and carbon tetrachloride or a mixture thereof may be used. Thecarbon dioxide may be bubbled in gas phase. Alternatively, solid dry icemay be used. It is also possible to carry out the reaction in thesupercritical state. The ammonium carbamate, ammonium carbonate orammonium bicarbonate and derivatives thereof used in the presentinvention may be prepared by any of the foregoing methods or any otherknown methods, as long as the final structure is the same. That is,solvent, reaction temperature, concentration, catalyst, etc. are notparticularly restricted and preparation yield is not restricted, either.

It is also possible to use a composite ammonium compound prepared byreacting an amine compound with carbon dioxide and a triatomic molecule.For example, the adduct formed by reacting nitrogen dioxide, sulfurdioxide or carbon disulfide with such an amine compound as propylamine,decylamine and octadecyl amine may be added to an ammonium compound orthe triatomic molecule may be added along with carbon dioxide during thereaction with amine to prepare the composite ammonium carbamate orcarbonate compound, as presented in Langmuir, 19, p1017 (2003) andLangmuir, 19, p8168 (2003). Besides, the compound obtained by reactingan amine compound with such a boron compound as boraic acid and boronicor such ammonium compound as ammonium sulfamate, ammonium sulfate,ammonium hydrogen sulfate, ammonium sulfite or a mixture thereof may beused. In addition, excess amine compound or such additive as surfactant,wetting agent, etc. may be comprised in the etching solution.

Such prepared ammonium carbamate, ammonium carbonate or ammoniumbicarbonate compound is reacted with oxidant to prepare an etchingsolution. For example, an oxidant may be reacted with at least one ofthe ammonium compound represented by the formula (1), (2) or (3) undernormal pressure or applied pressure with or without a solvent. In case asolvent is used, water, alcohols such as methanol, ethanol, isopropanol,butanol and ethanolamine, glycols such as ethylene glycol and glycerine,acetates such as ethyl acetate, butyl acetate and carbitol acetate,ethers such as diethyl ether, tetrahydrofuran and dioxane, ketones suchas methyl ethyl ketone and acetone, hydrocarbon solvents such as hexaneand heptane, aromatic solvents such as benzene and toluene,halogen-substituted solvents such as chloroform, methylene chloride andcarbon tetrachloride or a mixture thereof may be used.

Alternatively, a mixture solution comprising an oxidant and at least oneamine compound may be reacted with carbon dioxide to obtain an etchingsolution. In this case, the reaction may be carried out under normalpressure or applied pressure with or without a solvent, as describedabove. However, the method for preparing the etching solution of thepresent invention needs not be particularly restricted. That is, anyknown method can be applied, as long as the objects of the presentinvention can be attained. For example, solvent, reaction temperature,concentration, additive, etc. are not particularly restricted andpreparation yield is not restricted, either.

Specific examples of the oxidant, which is comprised in the etchingsolution for silver or silver alloy in accordance with the presentinvention as one of main components, are oxidative gases such as air,oxygen and ozone, peroxides such as hydrogen peroxide (H₂O₂), Na₂O₂,KO₂, NaBO₃, K₂S₂O₈, (NH₄)₂S₂O₈, Na₂S₂O₈, H₂SO₅, KHSO₅, (CH₃)₃CO₂H and(C₆H₅CO₂)₂, peroxy acids such as HCO₃H, CH₃CO₃H, CF₃CO₃H, C₆H₅CO₃H andm-ClC₆H₅CO₃H, oxidative inorganic acids such as nitric acid, sulfuricacid, I₂, FeCl₃, Fe(NO₃)₃, Fe₂(SO₄)₃, K₃Fe(CN)₆, (NH₄)₂Fe(SO₄)₂,Ce(NH₄)₄(SO₄)₄, NaIO₄, KMnO₄ and K₂CrO₄, metals and non-metal compounds.Such oxidant may be used alone or in combination. Differently fromconventional etching solutions, which are mainly composed of inorganicacids and, thus, are strongly acidic, the etching solution of thepresent invention is neutral to mild basic. Consequently, it isnon-corrosive and stable against light or heat.

Examples of metals that can form alloy along with silver are transitionmetals such as Au, Cu, Ni, Co, Pd, Pt, Ti, V, Mn, Fe, Cr, Zr, Nb, Mo, W,Ru, Cd, Ta, Re, Os and Ir, metals or non-metals such as Al, Ga, Ge, In,Sn, Sb, Pb, Bi, Si, As and Hg, lanthanides such as Sm and Eu, actinidessuch as Ac and Th and alkaline earth metals such as Mg, Ca, Sr and Ba.Typically, palladium, copper, gold, ruthenium, tin, neodymium, bismuth,silicon, germanium, magnesium, vanadium or a mixture thereof may be usedto obtain a silver alloy. The content of the metal comprised in thealloy or the amount of the oxidant needs not be particularly restricted,as long as the objects of the present invention are attained. And, thesilver or silver alloy to be etched may be in any form, including thinfilm, foil, wire, particle, etc.

Etching of silver or silver alloy using the etching solution may becarried out by heating, electrolysis, ultrasonification, microwavetreatment, high frequency treatment, plasma treatment, IR treatment, UVtreatment, etc. After etching of silver or silver alloy, the etchingsolution may be collected for reuse. The collected etching solution maybe used, for example, to prepare metal wiring or conductive ink or pastefor patterning or, through reduction or heat treatment, to preparehigh-purity silver, silver compounds or alloys, as presented in KoreanPatent Application No. 2005-11475, Korean Patent Application No.2005-11478, Korean Patent Application No. 2005-18364

and Korean Patent Application No. 2005-23013.

The etching solution of the present invention can attain the objects ofthe present invention as long as it comprises an ammonium compound andan oxidant. Specific composition will vary depending on the etching rateand etching amount. Also, a solvent may or may not be used, withoutparticular restriction.

ADVANTAGEOUS EFFECTS

The present invention provides an etching solution for silver or silveralloy which comprises at least one ammonium carbamate or ammoniumcarbonate compound represented by the formula (1), (2) or (3) and anoxidant.

The etching solution of the present invention is non-corrosive andstable while offering superior etching performance and enabling reuse.Thus, it can be widely utilized as the etching solution for silver orsilver alloy used in electrodes, wirings, reflection films,semi-transmission films, etc. in such applications as EMI shieldingmaterials, conductive adhesives, low-resistance metal wirings, printedcircuit boards (PCB), flexible printed circuits (FPC), antennas forradio frequency identification (RFID) tags, solar cells, secondarycells, fuel cells, plasma display panels (PDP), thin film transistorliquid crystal displays (TFT-LCD), organic light emitting diodes (OLED),flexible displays and organic thin film transistors (OTFT) and theetching solution.

BEST MODE

Hereinafter, the embodiments of the present invention will be describedin detail with reference to examples. However, it will be appreciatedthat those skilled in the art, in consideration of this disclosure, maymake modifications and improvements within the spirit and scope of thepresent invention.

EXAMPLE 1

In a 50.00 mL flask equipped with a stirrer, 2.26 g (13.93 mmol) ofisopropylammonium isopropylcarbamate was dissolved in 10.00 mL ofmethanol and 1.58 g (23.23 mmol) of 50.00 wt % aqueous hydrogen peroxidesolution was slowly added to obtain a colorless, transparent solution.Subsequently, metallic silver was slowly added at room temperature untilit was not dissolved any more. As the reaction proceeded, the reactionmixture turned into a gray slurry, and then into a colorless,transparent solution, again. The total amount of consumed silver was0.50 g (4.64 mmol).

COMPARATIVE EXAMPLE 1

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 1.74 g (13.93 mmol) of 28.00 wt % aqueous ammoniasolution was used instead of isopropylammonium isopropylcarbamate. Thetotal amount of consumed silver was 0.11 g (1.02 mmol).

COMPARATIVE EXAMPLE 2

In a 50.00 mL flask equipped with a stirrer, 8.55 g of 85.00 wt %phosphoric acid (85.50 wt % based on the total weight), 0.53 g of 60.00wt % nitric acid (5.30 wt % based on the total weight), 0.65 g of 99.00wt % acetic acid (6.50 wt % based on the total weight) and 0.27 g ofwater (2.70 wt % based on the total weight) were added to obtain acolorless, transparent solution. Subsequently, metallic silver wasslowly added at room temperature until it was not dissolved any more. Asthe reaction proceeded, the reaction mixture turned into a gray slurry,a yellow-green solution and then into a white, semitransparent solution.The total amount of consumed silver was 0.23 g (2.13 mmol).

EXAMPLE 2

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 4.52 g (27.86 mmol) of isopropylammoniumisopropylcarbamate was used. The total amount of consumed silver was0.57 g (5.28 mmol).

EXAMPLE 3

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 3.16 g (46.46 mmol) of 50.00 wt % hydrogenperoxide aqueous solution was used. The total amount of consumed silverwas 0.58 g (5.38 mmol).

EXAMPLE 4

A colorless, transparent solution was obtained in the same manner as inExample 1, except that a mixture of 5.00 mL of methanol and 5.00 mL ofwater was used instead of 10.00 mL of methanol. The total amount ofconsumed silver was 0.38 g (3.52 mmol).

EXAMPLE 5

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 2.51 g (13.93 mmol) of isopropylammoniumisopropylcarbonate was used instead of isopropylammoniumisopropylcarbamate. The total amount of consumed silver was 0.31 g (2.83mmol).

EXAMPLE 6

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 1.69 g (13.93 mmol) of isopropylammoniumbicarbonate was used instead of isopropylammonium isopropylcarbamate.The total amount of consumed silver was 0.32 g (2.97 mmol).

EXAMPLE 7

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 4.21 g (13.93 mmol) of 2-ethylhexylammonium2-ethylhexylcarbamate was used instead of isopropylammoniumisopropylcarbamate. The total amount of consumed silver was 0.15 g (1.39mmol).

EXAMPLE 8

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 2.71 g (13.93 mmol) of 2-methoxyethylammonium2-methoxyethylcarbamate was used instead of isopropylammoniumisopropylcarbamate. The total amount of consumed silver was 0.28 g (2.60mmol).

EXAMPLE 9

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 1.91 g (13.93 mmol) of 2-methoxyethylammoniumbicarbonate was used instead of isopropylammonium isopropylcarbamate.The total amount of consumed silver was 0.05 g (0.46 mmol).

EXAMPLE 10

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 1.09 g (13.93 mmol) of ammonium carbamate wasused instead of isopropylammonium isopropylcarbamate. The total amountof consumed silver was 0.22 g (2.04 mmol).

EXAMPLE 11

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 1.26 g (6.97 mmol) of isopropylammoniumisopropylcarbonate and 0.80 g (6.97 mmol) of ammonium sulfamate wereused instead of isopropylammonium isopropylcarbamate and that the sameamount of water was used instead of methanol. The total amount ofconsumed silver was 0.09 g (0.84 mmol).

EXAMPLE 12

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 1.26 g (18.56 mmol) of 50.00 wt % hydrogenperoxide aqueous solution and 0.49 g (4.64 mmol) of 60.00 wt % nitricacid were used instead of 1.58 g of 50.00 wt % hydrogen peroxide aqueoussolution. The total amount of consumed silver was 0.19 g (1.72 mmol).

EXAMPLE 13

A colorless, transparent solution was obtained in the same manner as inExample 1, except that 10.00 mL of water was used instead of methanol.The total amount of consumed silver was 0.08 g (0.76 mmol).

EXAMPLE 14

A colorless, transparent solution was obtained in the same manner as inExample 1, except that silver-palladium alloy (palladium content=1.00%)was added instead of metallic silver. The total amount of consumedsilver-palladium alloy was 0.48 g.

EXAMPLE 15

In a 50.00 mL flask equipped with a stirrer, 1.65 g (9.28 mmol) of 2:1(molar ratio) mixture of isopropylamine and boronic acid was dissolvedin 11.65 mL of methanol and 1.58 g (23.23 mmol) of 50.00 wt % aqueoushydrogen peroxide solution was slowly added to obtain a colorless,transparent solution. Subsequently, metallic silver was slowly added atroom temperature until it was not dissolved any more. As the reactionproceeded, the reaction mixture turned into a gray slurry, and then intoa colorless, transparent solution, again. The total amount of consumedsilver was 0.22 g (2.04 mmol).

INDUSTRIAL APPLICABILITY

The etching solution of the present invention is non-corrosive andstable while offering superior etching performance and enabling reuse.Thus, it can be widely utilized as the etching solution for silver orsilver alloy used in electrodes, wirings, reflection films,semi-transmission films, etc. in such applications as EMI shieldingmaterials, conductive adhesives, low-resistance metal wirings, printedcircuit boards (PCB), flexible printed circuits (FPC), antennas forradio frequency identification (RFID) tags, solar cells, secondarycells, fuel cells, plasma display panels (PDP), thin film transistorliquid crystal displays (TFT-LCD), organic light emitting diodes (OLED),flexible displays and organic thin film transistors (OTFT) and theetching solution.

Those skilled in the art will appreciate that the concepts and specificembodiments disclosed in the foregoing description may be readilyutilized as a basis for modifying or designing other embodiments forcarrying out the same purposes of the present invention. Those skilledin the art will also appreciate that such equivalent embodiments do notdepart from the spirit and scope of the present invention as set forthin the appended claims.

1. An etching solution for silver or silver alloy comprising at leastone ammonium compound represented by the formula (1), (2) or (3) belowand an oxidant:

each of R₁, R₂, R₃, R₄, R₅ and R₆ is, independently, selected fromhydrogen; substituted or unsubstituted C₁-C₃₀ aliphatic alkyl, alicyclicalkyl, aryl or aralkyl; a polymer compound; a heterocyclic compound; andderivatives thereof and R₁ and R₂ or R₄ and R₅ may be connected to forma ring.
 2. The etching solution for silver or silver alloy as set forthin claim 1, wherein each of R₁, R₂, R₃, R₄, R₅ and R₆ is, independently,selected from hydrogen, methyl, ethyl, propyl, isopropyl, butyl,isobutyl, amyl, hexyl, ethylhexyl, heptyl, octyl, isooctyl, nonyl,decyl, dodecyl, hexadecyl, octadecyl, docodecyl, cyclopropyl,cyclopentyl, cyclohexyl, allyl, hydroxy, methoxy, methoxyethyl,methoxypropyl, cyanoethyl, ethoxy, butoxy, hexyloxy, methoxyethoxyethyl,methoxyethoxyethoxyethyl, hexamethyleneimine, morpholine, piperidine,piperazine, ethylenediamine, propylenediamine, hexamethylenediamine,triethylenediamine, pyrrole, imidazole, pyridine, carboxymethyl,trimethoxysilylpropyl, triethoxysilylpropyl, phenyl, methoxyphenyl,cyanophenyl, phenoxy, tolyl, benzyl, polyallylamine andpolyethyleneamine.
 3. The etching solution for silver or silver alloy asset forth in claim 1, wherein the ammonium carbamate compoundrepresented by the formula (1) is selected from ammonium carbamate,ethylammonium ethylcarbamate, isopropylammonium isopropylcarbamate,n-butylammonium n-butylcarbamate, isobutylammonium isobutylcarbamate,t-butylammonium t-butylcarbamate, 2-ethylhexylammonium2-ethylhexylcarbamate, octadecylammonium octadecylcarbamate,2-methoxyethylammonium 2-methoxyethylcarbamate, 2-cyanoethylammonium2-cyanoethylcarbamate, dibutylammonium dibutylcarbamate,dioctadecylammonium dioctadecylcarbamate, methyldecylammoniummethyldecylcarbamate, hexamethyleneiminium hexamethyleneiminecarbamate,morpholinium morpholinecarbamate, pyridinium ethylhexylcarbamate,triethylenediaminium isopropylcarbamate, benzylammonium benzylcarbamateand triethoxysilylpropylammonium triethoxysilylpropylcarbamate.
 4. Theetching solution for silver or silver alloy as set forth in claim 1,wherein the ammonium carbonate compound represented by the formula (2)is selected from ammonium carbonate, ethylammonium ethylcarbonate,isopropylammonium isopropylcarbonate, n-butylammonium n-butylcarbonate,isobutylammonium isobutylcarbonate, t-butylammonium t-butylcarbonate,2-ethylhexylammonium 2-ethylhexylcarbonate, 2-methoxyethylammonium2-methoxyethylcarbonate, 2-cyanoethylammonium 2-cyanoethylcarbonate,octadecylammonium octadecylcarbonate, dibutylammonium dibutylcarbonate,dioctadecylammonium dioctadecylcarbonate, methyldecylammoniummethyldecylcarbonate, hexamethyleneiminium hexamethyleneiminecarbonate,morpholinium morpholinecarbonate, benzylammonium benzylcarbonate,triethoxysilylpropylammonium triethoxysilylpropylcarbonate andtriethylenediaminium isopropylcarbonate.
 5. The etching solution forsilver or silver alloy as set forth in claim 1, wherein the ammoniumbicarbonate compound represented by the formula (3) is selected fromammonium bicarbonate, isopropylammonium bicarbonate, t-butylammoniumbicarbonate, 2-ethylhexylammonium bicarbonate, 2-methoxyethylammoniumbicarbonate, 2-cyanoethylammonium bicarbonate, dioctadecylammoniumbicarbonate, pyridinium bicarbonate and triethylenediaminiumbicarbonate.
 6. The etching solution for silver or silver alloy as setforth in claim 1, wherein the oxidant comprises at least one componentselected from oxidative gas, peroxide, peroxy acid, oxidative inorganicacid, oxidative metal compound and oxidative non-metal compound.
 7. Theetching solution for silver or silver alloy as set forth in claim 6,wherein the oxidant comprises at least one component selected from air,oxygen, ozone, hydrogen peroxide, Na₂O₂, KO₂, NaBO₃, K₂S₂O₈, (NH₄)₂S₂O₈,Na₂S₂O₈, H₂SO₅, KHSO₅, (CH₃)₃CO₂H, (C₆H₅CO₂)₂, HCO₃H, CH₃CO₃H, CF₃CO₃H,C₆H₅CO₃H, m-ClC₆H₅CO₃H, nitric acid, sulfuric acid, I₂, FeCl₃, Fe(NO₃)₃,Fe₂(SO₄)₃, K₃Fe(CN)₆, (NH₄)₂Fe(SO₄)₂, Ce(NH₄)₄(SO₄)₄, NaIO₄, KMnO₄ andK₂CrO₄.
 8. The etching solution for silver or silver alloy as set forthin claim 1, wherein the silver alloy comprises at least one metalcomponent selected from Au, Cu, Ni, Co, Pd, Pt, Ti, V, Mn, Fe, Cr, Zr,Nb, Mo, W, Ru, Cd, Ta, Re, Os, Ir, Al, Ga, Ge, In, Sn, Sb, Pb, Bi, Si,As, Hg, Sm, Eu, Th, Mg, Ca, Sr and Ba.
 9. The etching solution forsilver or silver alloy as set forth in claim 1, which further comprisesa solvent or an additive.
 10. The etching solution for silver or silveralloy as set forth in claim 9, wherein the solvent comprises at leastone component selected from water, alcohol, glycol, acetate, ether,ketone, aromatic compound and halogenated hydrocarbon.
 11. The etchingsolution for silver or silver alloy as set forth in claim 10, whereinthe solvent is at least one component selected from water, methanol,ethanol, isopropanol, 1-methoxypropanol, butanol, ethylhexyl alcohol,terpineol, ethylene glycol, glycerine, ethyl acetate, butyl acetate,methoxypropyl acetate, carbitol acetate, ethylcarbitol acetate,methylcellosolve, butylcellosolve, diethyl ether, tetrahydrofuran,dioxane, methyl ethyl ketone, acetone, dimethylformamide,1-methyl-2-pyrrolidone, dimethylsulfoxide, hexane, heptane, dodecane,paraffin oil, mineral spirit, benzene, toluene, xylene, chloroform,methylene chloride, carbon tetrachloride and acetonitrile.
 12. Theetching solution for silver or silver alloy as set forth in claim 9,wherein the additive comprises at least one component selected fromammonium sulfamate, ammonium sulfate, ammonium hydrogen sulfate andammonium sulfite.
 13. The etching solution for silver or silver alloy asset forth in claim 1, wherein an composite ammonium compound prepared byadding at least one component selected from nitrogen dioxide, sulfurdioxide, carbon disulfide, boraic acid and boronic acid along withcarbon dioxide is used in preparing the compound represented by theformula (1), (2) or (3).
 14. A method for etching silver or silver alloyby adding silver or silver alloy to the etching solution as set forth inclaim 1 and carrying out at least one treatment selected from heating,ultrasonification, microwave treatment, high frequency treatment, plasmatreatment, IR treatment and UV treatment.